The present disclosure relates to pH sensors incorporating palladium electrodes and processes for manufacturing such sensors. They find particular application in conjunction with the biochemical and biological arts, and will be described with particular reference thereto. The pH sensors are suitable for use in applications such as wearable biomedical electronic devices.
Wearable biomedical electronic devices have recently attracted extensive research attention, as these devices could be of extreme importance in both early diagnosis through continuous monitoring of complex health conditions and in patients undergoing treatments. The pH value is a very useful indicator for disease diagnostics, medical treatment optimization, and constant monitoring of biochemical and biological processes of the human body. Therefore, developing highly reliable and conformable pH sensors for future wearable biomedical electronic devices is desired.
Although there are many different portable pH sensors available, in view of their rates of power consumption, architecture, and cost, they are not suitable for future wearable electronic applications. One promising direction is to use metal or metal oxide based sensing electrodes through the well-known and simple potentiometric method for pH sensing. Such metal or metal oxide sensors provide the advantages of simple structure design, low manufacturing costs, compatibility with miniaturization processes, and high sensitivity.
Gold is often used in electrodes for metal or metal oxide based pH sensors. Although gold itself shows some pH sensitivity (typically 23-26 mV/pH), metal oxides such as TiO2, ZnO, WO3, SnO2, RuO2, Ta2O5, PdO, or IrO2 are often coated on gold electrodes to increase sensitivity.
It would be desirable to produce pH sensors that have electrodes made from a lower-cost alternative metal to gold, but still show comparable or better pH sensitivity to sensors with gold electrodes.